I recently read “Soundbite” by Sara Harberson, and I’m pretty sure she says not to include anything in your applications that indicates that you have MH or learning issues, even if you have worked through them. Technically schools are not supposed to discriminate, but her opinion (as a former AO) is that they definitely do.
I have no evidence to support this, but I suspect that AOs are going to be favoring for the kids who found ways to keep themselves afloat and moving forward, even if slowly, without sinking, so that’s the impression I’d try to give unless the question asks very specifically about mental health. It was an unusual circumstance and I firmly believe it shouldn’t reflect poorly on any kid if they ended up depressed, but I also believe it’s not a bad idea to keep that information somewhat private.
If there are other problems your S encountered (loss of ECs, loss of contact with extended family, missed family traditions like an annual reunion, missed summer opportunities he was really looking forward to), I would focus on how he solved those problems or found other things to fill the time/keep him busy instead. Others here, however, may have different opinions about including true MH issues with good reasons, so I’m not 100% set on this; just 99% at this point in time.